CN214660925U - Centrifugal pump - Google Patents

Abstract

The present application relates to a centrifugal pump, comprising a pump body assembly comprising a pump sleeve (22) and a plurality of impeller stage sets, each impeller stage set comprising: a support body assembly (300) and a vane cavity assembly, and an impeller assembly (100), the impeller assembly (100) comprising an impeller hub (110), an impeller (120), and an impeller seat (130), a lower end face of the impeller hub (110) having attached thereto an anti-wear attachment (150) defining a rotational interface (152), the impeller axial support assembly comprising an outer housing (210), an inner housing (220), and vanes (230) connected between the outer housing (210) and the inner housing (220), and a stationary support (250) attached to the inner housing (220), the stationary support (250) comprising a stationary interface (254) engaged with the rotational interface (152) such that axial forces of the impeller assembly (100) are transferred to the inner housing (220) and then to a pump sleeve (22).

Description

Centrifugal pump

Technical Field

The application relates to a centrifugal pump, in particular to a high-speed and high-lift multistage centrifugal pump for a deep well.

Background

A deep well centrifugal pump generally includes a motor assembly and a pump body assembly containing an impeller driven to rotate by a pump shaft. The pump shaft rotating speed of the traditional centrifugal pump is about 3000rpm generally, and if the lift of water output by the centrifugal pump reaches 300m, the height of the centrifugal pump can reach 3m generally, so that the deep well pump is large in size and heavy.

Centrifugal pumps for deep wells are mostly used for agricultural irrigation, and the use environment is usually in the underground at different depths of 100m-500 m. In the application of severe natural environment such as high mountain, the operation is very inconvenient. In particular, the personnel are manually lifted to the top of the hill, which may take several hours or even a day, for the handling of the centrifugal pump alone, and it is very difficult to install the centrifugal pump, which is bulky and heavy, at the bottom of the shaft with a depth of several hundred meters and for possible subsequent maintenance. This limits the application of centrifugal pumps to a large extent.

In the process of improving the pump, in order to increase the lift of the centrifugal pump, a measure of enlarging the diameter of the impeller is generally adopted, which further increases the volume and weight of the pump, and aggravates the above inconvenience of the pump.

It is desirable to simplify the construction of the pump.

SUMMERY OF THE UTILITY MODEL

The object of the present application is to provide a centrifugal pump for deep wells which has high power, high lift, but reduced volume and weight.

To this end, the present application provides a centrifugal pump comprising a pump sleeve and a plurality of impeller stage sets housed within the pump sleeve, each impeller stage set comprising: an impeller assembly driven by a pump shaft of the centrifugal pump to rotate therewith, an impeller axial support assembly surrounding a lower half of the impeller assembly and providing axial support, and a support body assembly surrounding an upper half of the impeller assembly and providing support thereto, the impeller axial support assembly and the support body assembly being mechanically connected together to form an impeller cavity housing the impeller assembly, wherein:

the impeller assembly includes an impeller hub defining an impeller interface with the pump shaft, an impeller extending radially outward from the impeller hub, and an impeller seat attached to a radially outer periphery of the impeller, a lower end surface of the impeller hub having attached thereto an anti-wear attachment defining a rotational interface,

the impeller axial support assembly includes an outer housing mechanically connected with a support body assembly and attached to a pump sleeve, an inner housing surrounding a portion of an outer peripheral surface of the impeller hub, and vanes connected between the outer and inner housings, and a stationary support attached to the inner housing, the stationary support including a stationary engagement surface engaging the rotating engagement surface such that axial forces of the impeller assembly are transferred to the inner housing and then to the pump sleeve.

In one embodiment, the anti-wear attachment is embedded in a groove formed on the lower end face of the impeller hub, or attached to at least a portion of the lower end face of the impeller hub.

In one embodiment, the wear attachment is a tungsten steel annulus.

In one embodiment, the stationary support is attached to the inner housing directly or via an intermediate piece.

In one embodiment, the stationary support is a ceramic annulus.

In one embodiment, the impeller and the impeller seat define an impeller channel, and the outer housing, the inner housing, and the vanes define a flow guide channel in fluid communication with the impeller channel.

In one embodiment, the impeller includes a tapered portion extending outward in a radial direction and expanding upward in an axial direction from an axial position of an outer peripheral surface of an impeller hub, and blades spirally extending from a lower surface of the tapered portion, the impeller seat being attached to radially outer peripheries of the blades.

In one embodiment, the lower surface is angled between 40 ° and 70 ° from the axial direction.

In one embodiment, the outer housing of the impeller axial support assembly is joined to the impeller seat by an intermediate ring comprising an axial extension extending substantially in an axial direction and a radial extension extending radially outwardly therefrom transverse to the axial extension, the axial extension being located radially inwardly of the impeller seat and defining a first space therebetween, the radial extension being located below the impeller seat and defining a second space therebetween.

In one embodiment, the radially outermost tips of the vane seats of the impellers of each impeller stage group and the corresponding support body assembly define an annular gap therebetween that allows impurities in the water to pass therethrough.

In one embodiment, the plurality of impeller stage sets includes a first impeller stage set nearest the motor assembly of the centrifugal pump, the impeller axial support assembly corresponding to the first impeller stage set being an inlet housing assembly, the support body assembly of the first impeller stage set being radially connected to the vane cavity assembly of the impeller stage set adjacent thereabove.

In one embodiment, the plurality of impeller stage sets includes an additional impeller stage set located above the first impeller stage set, and the impeller axial support assembly corresponding to the additional impeller stage set is a vane cavity assembly.

In one embodiment, the pump shaft is a six-tooth pump shaft including six key teeth distributed in a circumferential direction.

According to the centrifugal pump, the axial force borne by the impeller assembly in each impeller stage group is transmitted to the guide vane cavity assembly and then transmitted to the pump sleeve through the impeller, the impeller assembly is not overlapped on the adjacent impeller stage group below, the axial force is not overlapped, and the loss of pump efficiency and pump power brought by the axial force is reduced. Under the condition of realizing the same lift, the height and the weight of the pump are reduced by about two thirds, and the application universality and the easiness of the centrifugal pump are greatly improved.

Drawings

The foregoing and other features, advantages and benefits of the present application will be described in detail below with reference to the drawings, in conjunction with exemplary embodiments of the present application. It is to be understood that the drawings are not to scale and are merely illustrative of the principles of the application and are not intended to limit the application to the embodiments illustrated. The components shown in the drawings do not necessarily have to be present in all embodiments of the application, and components not shown in the drawings may be present in some embodiments of the application.

FIG. 1 is a longitudinal section of an exemplary centrifugal pump of the present application;

FIG. 2 is a partially exploded view of the centrifugal pump of FIG. 1;

FIG. 3 is an enlarged view of an impeller assembly and a vane cavity assembly of a second set of impeller stages of the centrifugal pump of FIG. 1;

FIG. 4 is a cross-sectional view of a pump shaft of an exemplary centrifugal pump of the present application.

Detailed Description

The centrifugal pump of the present application is described in detail below with reference to the accompanying drawings. Throughout the drawings, parts that are structurally or functionally the same or similar have the same reference numerals.

Fig. 1 and 2 show an axial sectional view and a partially exploded view, respectively, of the centrifugal pump of the present application. Generally, a centrifugal pump includes a motor assembly 10 and a pump body assembly 20. The motor assembly 10 includes a motor housing and a motor, such as an electric motor, accommodated in the motor housing and capable of outputting a high rotational speed. An auxiliary system, such as a cooling system, that provides auxiliary functions for the operation of the motor is also provided within the motor housing. The pump block assembly 20 includes a pump sleeve 22 and a plurality of impeller stage sets housed within the pump sleeve 22. The output shaft of the motor drives the impellers of each impeller stage group in the centrifugal pump to rotate through the pump shaft 11 of the centrifugal pump. In the illustrated embodiment, the pump shaft 11 is a six-tooth pump shaft, and fig. 4 shows an enlarged cross-sectional view of the pump shaft 11, in which the pump shaft 11 includes a body 111 and six protrusions 113 uniformly arranged from the outer circumferential surface of the body 111.

In the present application, for convenience of description, the direction in which the pump shaft 11 extends is defined as an axial direction, and the circumferential direction extends around the axial direction. The centrifugal pump of the present application is normally placed vertically during use, so the axial direction is also referred to as the vertical direction, the direction/end in the axial direction towards the motor assembly 10 is referred to as the lower/lower end, and the opposite direction/end is referred to as the upper/upper end. In a plane perpendicular to the axial direction, a direction from the pump sleeve 22 toward the central axis of the pump shaft 11 is referred to as radially inward, and conversely, a direction from the central axis of the pump shaft 11 toward the pump sleeve 22 is referred to as radially outward, with reference to the central axis of the pump shaft 11 defining the axial direction.

Referring again to fig. 1 and 2, the pump body assembly 20 includes, in order in an axial direction, from bottom to top, a water intake section 30, an impeller section 50 comprised of a plurality of impeller stages, and a water outlet section 40.

In the water inlet section 30, water inlet holes 32 distributed in the circumferential direction are provided on the pump sleeve 22, and in the water inlet section 30, a cone housing 34 is provided inside the pump sleeve 22. The cone housing 34 is configured as an inverted cone that opens toward the motor assembly 10, including a central aperture that allows the pump shaft 11 to pass through. A pump shaft connection portion that connects the pump shaft 11 to an output shaft of the motor assembly 10 and supports the pump shaft 11 is disposed within a space 33 formed by an inner surface 37 of the cone housing 34 facing the motor assembly 10. An opposite outer surface 39 of cone housing 34 and pump sleeve 22 define a water inlet space 35 in fluid communication with water inlet bore 32 for receiving water entering through water inlet bore 32 from outside the centrifugal pump. According to the present application, the water inlet 32 includes a plurality of water inlet groups spaced apart in the circumferential direction of the pump sleeve 22, each water inlet group including a plurality of water inlet holes densely distributed.

In the impeller section 50, 5 impeller stage groups B1-B5 arranged in series in the axial direction are mounted in sequence within the pump sleeve 22. Of course, the number of impeller stage sets of the centrifugal pump is not limited to 5, but may be varied according to actual requirements. The impeller stage set located lowermost in the centrifugal pump adjacent the water intake section 30 is referred to herein as the first impeller stage set, and is designated by reference numeral B1; the other sets of impeller stages, other than the first set of impeller stages, are referred to as other sets of impeller stages and are designated by reference numerals B2-B5.

Typically, in a centrifugal pump comprising a plurality of impeller stage sets B1-B5 as illustrated, for impeller stage sets B2-B5 other than the first impeller stage set B1 adjacent the water intake section 30, each impeller stage set comprises an impeller assembly 100 driven for rotation by the pump shaft 11, a vane cavity assembly 200 surrounding the lower half of the impeller assembly 100 and providing axial support, and a support body assembly 300 surrounding and providing support to the upper half of the impeller assembly 100. The first impeller stage set B1, the lowermost impeller stage set, has a slightly different configuration due to its proximity and connection to the water intake section 30 of the pump block assembly 20. the impeller assembly 100 of this first impeller stage set B1 also includes a support body assembly 300 surrounding its upper half, except that the lower half of the impeller assembly 100 is axially supported by a header assembly 200' that is slightly different in configuration from the vane cavity assembly 200 described above.

The inlet seat assembly 200 'providing axial support to the impeller assembly 100 of the first impeller stage set B1, while structurally different from the vane cavity assemblies 200 providing axial support to the impeller assemblies 100 of the other impeller stage sets B2-B5, the interface structure between the inlet seat assembly 200' and the impeller assembly 100 and between the vane cavity assembly 300 for the first impeller stage set B1 is the same as the interface structure between the vane cavity assembly 200 and the impeller assembly 100 and between the vane cavity assembly and the support body assembly 300 for the other impeller stage sets B2-B5. In this regard, the inlet block assembly 200' for the first impeller stage set B1 and the vane cavity assembly 200 for the other impeller stage sets B2-B5 are collectively referred to as "impeller axial support assemblies" in the description herein. That is, each impeller stage set B1-B5 of the centrifugal pump of the present application includes an impeller assembly 100, a support body assembly 300 and an impeller axial support assembly 200 or 200'.

For each impeller stage set, the support body assembly 300 and the impeller axial support assembly are mechanically coupled together to collectively form an impeller cavity that receives and supports the impeller stage set 100. The support body assembly 300 of each impeller stage set is mechanically connected to the impeller axial support assembly 200 or 200' of the impeller stage set adjacent thereabove, such that the impeller stage sets are mechanically connected together. Likewise, for each impeller stage set, the impeller assembly 100 defines an impeller passage 125 (see fig. 3) through which water is permitted to flow, and the impeller axial support assembly 200 or 200' defines a flow guide passage 225 (fig. 3) in fluid communication with the impeller passage 125. The impeller channels 125 of each impeller stage set are in fluid communication with the flow directing channels 225 of the adjacent impeller stage set located thereabove, thereby forming a continuous water flow channel throughout the impeller section 50. In other words, the impeller assemblies 110 and impeller axial support assemblies 200 or 200' of all of the impeller stage sets B1-B5 collectively define the water flow passage.

At the outlet section 40, which is located at the opposite end of the inlet section 30, includes an uppermost vane cavity assembly 410 connected to the support body assembly 300 of the last impeller stage set B5, a one-way valve assembly 420 mounted on the vane cavity assembly 410, and an outlet seat assembly 430 connected to the pump sleeve 22 and defining an outlet 432 (as shown in FIG. 1)

Fig. 3 illustrates, in enlarged form, a cross-sectional view of the coupled structure of the impeller assembly 100 and the impeller axial support assembly 200, as exemplified by the second impeller stage group B2. It should be understood by those skilled in the art that the interfacing structure of impeller assembly 100 and impeller axial support assembly 200 described below with respect to second impeller stage set B2 is applicable to all other impeller stage sets of centrifugal pumps, including first impeller stage set B1.

The construction of the impeller assembly 100 and the support body assembly 300 is the same for all impeller stage sets of the centrifugal pump. The impeller assembly 100 basically includes an impeller hub 110, an impeller 120 and an impeller seat 130. The impeller hub 110 is generally cylindrical in shape and defines a shaft bore 112 that allows the pump shaft 11 of the centrifugal pump to pass through and engage therewith. Typically, the impeller hub 110 and the pump shaft 11 may engage via a keyed engagement, a keyway in the shaft bore 112 being schematically illustrated in FIG. 3.

The impeller 120 includes a tapered portion 124 extending outwardly in a radial direction, for example, from the axial position P in the radial direction, and expanding upwardly in an axial direction, from an upper portion of the outer peripheral surface 114 of the impeller hub 110, and blades 126 extending spirally from a lower surface 123 of the tapered portion 124. The impeller seat 130 is located radially outward of the impeller 120 and is circumferentially attached to the impeller 120, specifically the radially outer periphery or free end of the blades 126. The impeller seat 130 includes an axial base portion 132 and an enlarged portion 134 extending radially outwardly and axially upwardly from the axial base portion 132. An impeller passage 125 allowing water to flow therethrough is formed between the impeller 120 and the impeller seat 130. In one embodiment of the present application, the impeller 120 and the impeller hub 110 are integrally formed, and the impeller seat 130 is attached to the outer circumference of the impeller 120 in any manner known in the art to rotate with the impeller 120. It will be understood by those skilled in the art that the impeller hub 110, impeller 120 and impeller seat 130 may each be formed separately and then attached together, or any two or three of them may be integrally formed.

As described above, the blades 126 of the impeller 120 protrude from the lower surface 123 of the tapered portion 124. In one embodiment, the lower surface 123 is angled between 20 ° and 50 ° from the horizontal, in other words, the lower surface 123 is angled between 40 ° and 70 ° from the central axis Z.

To the lower end face of the impeller hub 110 is attached a wear attachment 150. Wear attachment 150 may be attached and secured to the lower end face of impeller hub 110 by any suitable means, including, but not limited to, an interference fit, connection with fasteners, and the like, in any manner known in the art. In the illustrated embodiment, the wear attachment 150 is embedded in a groove formed on the lower end face of the impeller hub 110. The lower end surface 152 of the wear attachment 150 provides a rotational interface with the impeller axial support assembly 200. In embodiments not shown, it is contemplated that anti-wear attachment 150 may be attached to a portion of the lower end face of impeller hub 110 or cover the entire lower end face of impeller hub 110.

The impeller axial support assembly 200 comprises an outer casing 210 adapted to mechanically engage with a support body assembly 300 (not shown in fig. 3) of the impeller stage assembly and attached to the pump sleeve 22, and an inner casing 220 surrounding the lower half of the impeller stage assembly 100, in particular the lower part of the outer circumferential surface 114 of the impeller hub 110, the vanes 230 extending between the inner casing 220 and the outer casing 230, forming with the inner casing 220 and the outer casing 210 vane passages 225 allowing water to flow through.

In the illustrated embodiment, the intermediate piece 240 is fixedly attached to the inner housing 220, and a stationary support base 250 that directly contacts and supports the impeller assembly 100 is attached to the intermediate piece 240 and remains stationary during centrifugal pump operation. The intermediate piece 240 and the stationary support base 250 define shaft holes 242 and 252, respectively, through which the pump shaft passes. The stationary support base 250 includes an upper surface 254 for a stationary engagement surface for contacting the rotating engagement surface provided by the lower end surface 152 of the wear attachment 150.

As shown in fig. 3, in the assembled state of the impeller assembly 100 and the impeller axial support assembly 200, the lower end surface 152 of the wear attachment 150 rotating with the impeller assembly 100 at high speed engages the upper surface 254 of the stationary ceramic support base 250. The wear attachment 150 and the stationary support base 250 form a dynamic sealing engagement between the contacting surfaces that prevents water in the water flow path from entering the pump shaft bore through the axial gap 270 between the inner housing 220 and the impeller hub 110 of the impeller assembly 110. In one embodiment, the wear attachment 150 may be formed of a tungsten steel material and the stationary support base 250 may be formed of a ceramic material, the two materials being selected to minimize frictional resistance between the relatively moving wear attachment 150 and the stationary support base 250. Preferably, as shown in fig. 3, the notches 262 are uniformly distributed along the circumferential direction on the upper end surface 254 of the stationary support seat 250, and the arrangement of the notches 262 avoids or greatly reduces the molecular bonding force generated by the vacuum formed between the wear-resistant attachment 150 rotating at a high speed and the stationary support seat 250, greatly reduces the power loss of the centrifugal pump, and improves the efficiency of the pump.

As shown, the outer housing 210 of the impeller axial support assembly 200 is joined to the axial base 132 of the impeller seat 130 of the impeller assembly 100 by an intermediate ring 280. The intermediate ring 280 includes an axial extension 282 extending generally in an axial direction and a radial extension 284 extending radially outward therefrom transverse to the axial extension 282. A first space 292 is defined between the axial extension 282 and the axial base 132 of the impeller seat 130. The radial extension 284 defines a second space 294 with the axial base 132. The first space 292 has a width in the radial direction smaller than that of the second space 294 in the axial direction. The second space 294 may function as a pressure balance. Specifically, during operation of the centrifugal pump, water attempting to invade the water flow passage from the space radially outside the impeller seat 130 via the second space 294 and the first space 292 greatly decreases in velocity after entering the second space 294, so as not to continue to enter the first space 292, i.e., most, or even all, of the water is blocked in the second space 294. Meanwhile, water in the second space 294 is thrown out by a centrifugal force, thereby forming an internal water pressure against an external water pressure, so that the impeller 120 may not bear a radial force generated by the water. In addition, the above-mentioned water pressure balance also enables the impeller assembly 100, specifically the impeller seat 130 and the outer housing 210 to be always in a "sealing" state, and the sealing is not disabled due to the high-speed rotation of the impeller.

In the non-operational state of the centrifugal pump, the impeller assembly 100 fits within the axial impeller cavity formed by the support body assembly 300 and the impeller axial support assembly 200. The lower end surface 152 of wear attachment 150 is in axial contact with the upper end surface 254 of the stationary support 250 and the impeller axial support assembly 200 axially supports the impeller assembly 110 and the support body assembly 300.

In the operating state of the centrifugal pump, the impeller assembly 100 is driven by the pump shaft 11 to rotate at a high speed in the axial impeller cavity, and water is sucked in from the guide passage 225 defined by the impeller axial support assembly 200 by the suction force generated by the rotation of the impeller 120, enters the impeller passage 125 of the impeller 120, and is then thrown into the guide passage 225 of the next impeller stage group. At this time, as the lower end surface 152 of the wear attachment 150, which is rotating at high speed by the impeller assembly 100, is in axial contact and sealing engagement with the upper end surface 254 of the stationary support 250, any axial force experienced by the impeller assembly 120 is transferred to the stationary support 250 of the impeller axial support assembly 200 and then to the inner casing 220 and the outer casing 210. This axial force transmission causes friction between the two end faces 152 and 254 in contact with each other. To reduce the effect of this friction on the power and efficiency of the centrifugal pump, any surface treatment may be applied to the end faces 152 and 254 that are in contact with each other. In one embodiment, an anti-friction coating may be applied to the end faces 152 and 254. In the illustrated embodiment, tungsten steel and ceramic materials are selected to form the wear attachment 150 and the stationary support 250, respectively, to minimize frictional and molecular binding drag forces generated on both surfaces.

Further, as shown, an annular gap 80 (see fig. 1) allowing impurities, such as silt, in water to settle down is defined between the distal end 134a of the expansion portion 134 of the impeller seat 130 of the impeller assembly 100 and the support body assembly 300. Silt in the water stream flowing in impeller passage 125 passes through annular gap 80 and enters impurity collection space 90 defined by support body assembly 300 of impeller stage assembly 100, outer housing 220 of impeller axial support assembly 200, and impeller seat 130.

As described above, the axial forces experienced by impeller assembly 100 in each impeller stage set are transferred to impeller axial support assembly 200 (or the inlet seat assembly for first impeller stage set B1) and thus to pump sleeve 22 via the axial engagement of lower end surface 152 of wear attachment 150 with upper end surface 254 of stationary support seat 250 of impeller axial support assembly 200, without being superimposed on the underlying adjacent impeller stage set, thus not increasing the axial forces experienced by the underlying impeller stage set, and not creating a superposition of axial forces. Such an arrangement reduces pump power losses due to rotational friction resulting from the superposition of axial forces of the impeller assembly 100. On the other hand, the surface treatment of the contact end face or the selection of a specific material can further reduce the lost pump power and improve the pump working efficiency.

The centrifugal pump adopts a motor structure component with the output rotating speed of 12000 or higher and a pump body component structure schematically shown in the figure, and can obtain the water output lift of about 300m by only configuring 5 impeller stage groups. In this case, the centrifugal pump has a total height of only about 1 m. Even if the controller of the centrifugal pump is housed inside the centrifugal pump, the total height of the centrifugal pump is only about 1.5 m. Compared with the traditional centrifugal pump for the deep well, the height of the pump is shortened by half to two thirds, and the shortened height means great reduction of the weight of the centrifugal pump. The structure enables the application of the deep well centrifugal pump to be wider, simpler and easier.

Although the present invention is described above with reference to the embodiments shown in the drawings, it is apparent to one of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve similar results. It is therefore contemplated that all such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following non-limiting claims for all purposes.

Claims (13)

1. A centrifugal pump comprising a pump sleeve (22) and a plurality of impeller stage sets (B1-B5) housed within the pump sleeve, each impeller stage set comprising: an impeller assembly (100) driven by a pump shaft (11) of the centrifugal pump to rotate therewith, an impeller axial support assembly surrounding a lower half of the impeller assembly (100) and providing axial support, and a support body assembly (300) surrounding an upper half of the impeller assembly (100) and providing support thereto, the impeller axial support assembly and the support body assembly (300) being mechanically connected together to form an impeller cavity housing the impeller assembly (100), wherein:

the impeller assembly (100) includes an impeller hub (110) defining an engagement surface with the pump shaft (11), an impeller (120) extending radially outward from the impeller hub (110), and an impeller seat (130) attached to a radially outer periphery of the impeller (120), an anti-wear attachment (150) defining a rotational engagement surface (152) being attached to a lower end surface of the impeller hub (110),

the impeller axial support assembly comprises an outer housing (210) mechanically connected with a support body assembly (300) and attached to a pump sleeve (22), an inner housing (220) surrounding a portion of an outer circumferential surface of the impeller hub (110), and a guide vane (230) connected between the outer housing (210) and the inner housing (220), and a stationary support (250) attached to the inner housing (220), the stationary support (250) comprising a stationary engagement face (254) engaging the rotary engagement face (152) such that axial forces of the impeller assembly (100) are transferred to the inner housing (220) and then to the pump sleeve (22).

2. The centrifugal pump of claim 1, wherein the wear resistant attachment (150) is embedded in a groove formed on the lower end face of the impeller hub (110) or attached to at least a portion of the lower end face of the impeller hub (110).

3. A centrifugal pump according to claim 2, wherein the wear resistant accessory (150) is a tungsten steel annulus.

4. A centrifugal pump according to claim 1, wherein the stationary support (250) is attached to the inner housing (220) directly or via an intermediate piece (240).

5. A centrifugal pump according to claim 4, wherein the stationary support (250) is a ceramic annulus.

6. The centrifugal pump of claim 1, wherein the impeller (120) and impeller seat (130) define an impeller channel (125), and the outer housing (210), inner housing (220), and vanes (230) define a flow directing channel (225) in fluid communication with the impeller channel (125).

7. The centrifugal pump according to claim 1, wherein the impeller (120) includes a tapered portion (124) extending outward in a radial direction and expanding upward in an axial direction from an axial position (P) of the outer peripheral surface (114) of the impeller hub (110) and a vane (126) spirally extending from a lower surface (123) of the tapered portion (124), the impeller seat (130) being attached to a radially outer periphery of the vane (126).

8. A centrifugal pump according to claim 7, wherein the angle of the lower surface (123) to the axial direction is between 40 ° and 70 °.

9. A centrifugal pump according to any one of claims 1-8, wherein the outer casing (210) of the impeller axial support assembly is joined to the impeller seat (130) by an intermediate ring (280), the intermediate ring (280) comprising an axial extension (282) extending substantially in an axial direction and a radial extension (284) extending radially outwards therefrom transversely to the axial extension (282), the axial extension (282) being located radially inwards of the impeller seat (130) and defining a first space (292) therebetween, the radial extension (284) being located below the impeller seat (130) and defining a second space (294) therebetween.

10. The centrifugal pump of claim 9, wherein a radially outermost extremity (134a) of the vane seat of the impeller (120) of each impeller stage set and the corresponding support body assembly (300) define an annular gap (80) therebetween that allows passage of impurities in the water.

11. The centrifugal pump of any one of claims 1-8, wherein the plurality of impeller stage sets comprises a first impeller stage set (B1) closest to a motor assembly of the centrifugal pump, the impeller axial support assembly corresponding to the first impeller stage set (B1) being a header assembly, the support assembly (300) of the first impeller stage set (B1) being radially connected to the vane cavity assembly of the impeller stage set adjacent thereabove.

12. The centrifugal pump of claim 11, wherein said plurality of impeller stage sets includes other impeller stage sets located above a first impeller stage set (B1), the impeller axial support assemblies corresponding to said other impeller stage sets being vane cavity assemblies.

13. A centrifugal pump according to any one of claims 1-8, wherein the pump shaft (11) is a six-tooth pump shaft comprising six key teeth (111) distributed in the circumferential direction.

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